Apparatus and method for bending pipes, bars, plates, and like pieces



June 16, 1942.. P. BOISSOU 2,286,893

APPARATUS AND METHOD FOR BENDING PIPES, BARS, PLATES, AND LIKE PIECES Filed'Aug. 6, 1938 4 Sheet's-Sheet J.

P/E/P/PE Ba/ssd V N vslv ran June 16, 1942. P. BOISSOU 2,285,893

APPARATUS AND METHOD FOR BENDING P IPES BARS, PLATES, AND LIKE PIECES Filed Aug. 6, 1938 4 Sheets-Sheet 2 8 fur/ R5 84 N54 0 INVENTIR A l-t 977"? P. BOISSOU 2,286,893

APPARATUS AND METHOD FOR BENDING PIPES, BARS, PLATES, AND LIKE PIECES June 16, 1942.-

Filed Aug. 6, 1938 4 Sheets-Sheet. 5

PIERRE 54/515; 0

P. BOISSOU June 16, 1942 APPARATUS AND METHOD FOR BENDING PIPES, BARS, PLATES, AND LIKE PIECES Filed Aug. 6, 1938 4 Sheets-Sheet 4 Bus- Patented June 16, 1942 APPARATUS AND METHOD FOR. BENDING PIPES, BARS, PLATES, AND LIKEPIECES Pierre Boissou, Pont-a-Mousson, France, assignor to Societe Anonyme des Hauts Fourneaux et Fonderies dc Pont a Mousson, Pont-a-Mousson,

France Application August 6, 1938, Serial No. 223,429 In France August 23, 1937 6 Claims. (01. 153-32) Processes are known for the bending of pipes, such as cast iron pipes, and particularly centrifugated cast iron, which consist essentially in V displacing a heating burner by hand adjacent the pipe, in the region of the bend to be obtained. while at the same time the pipe is subjected to a bending stress.

The present invention has for its object to provide an improved process of the above-mentioned type for the automatic bending of pipes made of cast iron (and particularly of centrifugated cast iron), of steel, glass or any other material, and in general for the bending of pieces of any crosssection, as well as thick plates such as are used in naval construction.

The said process consists essentially in displacing automatically with respect to each other the piece to be bent and the burner or burners (these latter being situated in a common radial plane with the bend to be obtained), in such a way that the displacement will be dependent on the bending angle already obtained and on the radius of curvature desired in each cross-section of the bend or curve to be obtained. 1

If it is desired to obtain a circular'bend, the burner or burners, or the piece to-be bent, are displaced by an amount which is equal to the product of the above-mentionedangl'e expressed in radians multiplied by the constant radius of curvature which is desired.

If it is desired to obtain a bend having a spiral form, the burner or burners, or said piece, will be displaced according to any suitable law depending upon the aforesaid angle and the desired radii of curvature.

If it is desired to obtain a warped bend having the form of a helix, the burner or burners are displaced as above stated, and in addition the piece to be bent is turned on its axis by an angle which is proportional to the bending angle already obtained, and to the pitch of the winding desired, which two movements might be replaced by a single helical movement of said piece with reference to the burner, or inversely.

According to a further feature of the invention. applicable in the case in which the piece to be bent is tubulanuse is made of one or more burners or like heating devices which are situated and are movable in the interior of the pipe or other hollow piece to be bent.

This particular process is particularly advantageous, as it permits of avoiding the losses. ofheat which always take place at the exterior of a pipe. .'I'his afl'ords a' reat saving in the consumption of fuel, and'on the other hand, for the same reason, the operation is more rapid.

The invention has further for its object to provide a device for carrying into effect the abovementioned process.

The said device comprises means for fixedly holding one end or one edge of the piece to be bent, a suspendedweight or like means for excurvature to be obtained.

With a view to accelerate the bending operation, it may be of advantage to make use of two sets of burners for treating simultaneously two different portions of the pipe or other piece to be bent.

Further characteristics will be set forth in the following description.

In the accompanying drawings, which are given solely by way of example:

Figs. 1 to 6 are diagrammatic el'evational views of various simple forms of the device according to the invention, comprising a single burner or set of burners.

Fig. 7 is a similar view of an embodiment comprising two sets of burners.

Fig. 8 is a similar view, with parts broke away, of a device comprising an internal burner.

In the figures, like parts are designated by the same reference numerals.

According to the embodiment shown in Fig. 1, the invention is supposed to be applied to the bending of a pipe held in a horizontal position at one end between two pairs of jaws 5 and 6. At its free end I is suspended a weight 8 which exerts a bending stress in the different crosssections of the pipe, and particularly in the crosssection 8 which is adjacent a burner 9, and in which the bending of the pipe takes place at any one time.

In orderto obtain a regular bending, it is necessary and suflicient to displace the burner 9 under the part of the pipe which is to be bent, by an amount ab which is equal to the product of the desired radius of curvature R=0a, by the bending angle as expressed in radians which has already been obtained, 1. e. the angle through which:1 the free end 1 of the pipe has already turne This result is obtained by the following device,

- according to the invention.

by a set of jointed parallelograms II, or by Cardan joints, or like devices, with a crank arm l2, in such way that said crank arm will always be parallel to the collar Ill. The arm I2 is mounted on a shaft carrying a set of pulleys l4. Each pulley H has a radius equal to one of the radii of curvature R the obtainance of which is desired. Upon any one of said pulleys may be wound a cable or like flexible member l5, which passes over a supporting wheel l6, and is then attached at H to a carriage l8 which is movable upon a track I9, parallel to the fixed part of the pipe I. The carriage l8 carries the burner."

The operation of the device is as follows.

During the bending operation, the free end I of the pipe will gradually sink in the direction of the arrow by the action of the weight 8. The arm l2 will turn through a like angle in the direction of the arrow 1 thus moving the carriage in the directionof the arrow 1 by a distance which is at any one time equal to the product of the desired radius of curvature R bythe bending angle already obtained, i. e. by a value equal to the circumstantial development ab. Thus the curvature obtained at each point of the pipe I will be constant, and hence the resulting bend will have the form of a perfectly regular circular arc.

The said device is preferably completed by means owing to which the bending operation may be stopped when the desired curvature is obtained. This result can be attained for example by placing in the path of the carriage l'l a member which is actuated by the said carriage as soon as the desired bending is attained. Said member 20, which must be capable of occupying different predetermined positions on the track ill at a distance from the initial position of the carriage I8 corresponding to the desired length of the bend, may actuate for example, either an electric bell which gives warning to the man in charge of the machine, or even a valve which will cut off the feed to the burner, thus automatically interrupting the bending operation.

Fig. 2 shows another construction of the device According to this embodiment, there is rigidly secured to the free end of the pipe a sleeve It provided with an oblique arm 2|, which is terminated by a socket 22 situated at a distance 0c from the pipe I which is equal to the desired radius of curvature, the point 0 being at the origin of the bend. In said socket is rotatably mounted an axle 23 carried by an arm 24. The said arm is maintained by a weight 25 in a positionwhich is'always vertical, and forms a sort of pendulum. Its upper branch, whose length is somewhat less' than the desired radius of curvature, carries the burner 9.

operation will take place as if the part of the bend already curved, the collar NJ, the arm 2|, and the joint (22, 23) would turn constantly about an instantaneous centre of rotation which coincides with the section b. In consequence, as this section b is always situated below the joint (22, 23), this latter will be displaced, during the bending operation, on a path XX which is parallel to the straight part of the pipe, i. e. in such a manner that the distance ab representing the radius of curvature will be constant.

This very simple device will thus afford, on the one hand a very regular bending, and on the other hand, it provides for the automatic movement of the burner 9 during the bending opera tion.

A stop member 2. may be provided, as in the preceding case, upon the path XX.

Fig. 3 represents a device which closely resembles the one just described. The burner 9 is carried by a carriage II which is movable on a track I9 parallel to the fixed part of the pipe I (or bar or section iron) to be bent. Said carriage I1 is provided with an axle 23 upon which is rotatably mounted a sleeve 22 which is connected by two bars 2| and 2|a with a sector 26 concentric with the axle 23, and by an extension of the bar 2|, with a collar Ill mounted on the free end I of the pipe. The vertical distance ob between the said axle and the fixed part of the pipe. and the distance 00 between the said axle and the free part I of the pipe are the same, and are equal to the desired radius of curvature. The sector 26 carries a weight 2 by means of a cable 21 which is attached at 28 to the upper part of the sector.

Consequently, said weight exerts upon the bars 2| and Ma, and hence upon the section of the pipe or other piece which is being bent, a constant bending force. This feature is of special interest, as it gives regularity to the rate of the operation.

The ending operation takes place, as before, starting from the section 0, the resulting radius of curvature is constant, and any slight irregularities which might occur in practice with the device shown in Fig. 2 in the path of the joint (22, 23) are entirely eliminated, owing to the use of the track l9.

In the same manner as in the embodiment of Fig. 1, a member 20 disposed in the path of the carriage ll may actuate for example a valve 2 which is inserted in the feeding conduit 3 to the burner and which will cut off the feed to the burner, thus automatically interrupting the bending operation.

As thebar 2| has a constant direction with reference to the collar l0, it is possible, according to the invention, to replace the joint provided between these two members, by a rigid connection.

Fig. 4 represents a device resembling the one shown in Fig. 2, except that the pipe I or other piece) to be bent is mounted in a vertical position. The bending weight I is suspended by a socket 28 from an axle III mounted on a link 3| which is rigidly and obliquely secured to the free end I of the pipe by a collar Ill. The weight 8, which forms a sort of pendulum, also serves to maintain the burner 9 in the horizontal position by means of an arm 22 which is rigidly secured to the arm 32, at from this latter.

The distances 0b between the axle 30 and the fixed part of the pipe I, and 0c between the said axle and the free end I of the pipe, are equal to the desired radius of curvature.

The operation of this device is the-same as for the device above mentioned; but in this case, as the movement ofthe weight 2 is parallel to the pipe to be bent, the shearing stress in the bending section b is nil, and this aids in assuring the regularity of the resulting bend.

Moreover, as the distance between the pipe to be bent and the axle 30 is constant, the bending moment will also be constant, without requiring the use of a sector as in the, preceding case.

An automatic stop device may be mounted at 20 below the weight 8, which descends by a aaaasea distance equal to the length of the resulting bend.

Another embodiment is shown in Fig. 5. According to this example, two burners 3 and 3a are employed. The pipe Ixor other piece to be bent is mounted on two supports 34 and 34a. The burners 9 and 9a are carried by two arms 35 and 35a which are connected together by a joint 36, and the said joint is movable in a vertical slot 31 which is located at equal distances from the supports 34 and 34a.

The supports 35 and 35a are connected by arms 38 and 33a of two sleeves 33 and 39a which are slidable on the ends of the pipe. The sleeves and arms are so designed that the supports 35 and 35a will always be at right-angles to the ends of the pipe. The bending weight 8 is suspended, for instance, from the middle of the pipe.

The operation of the said device is as follows. When starting, the pipe I is straight and the two burners 9 "and 9a are located adjacent each other at the middle part of the pipe, and this arrangement permits of very rapidly obtaining the proper temperature in the middle section of the pipe.

When the bending action commences, the two burners will move apart by an amount which is proportional to the bending angle obtained, and to the radius of curvature which is equal to the length of the arms 35, 35a.

This device is particularly advantageous for the bending of pipes of large diameter.

The lengths and directions of the different rods are such that when the collars 43 are placed upon the straight pipe before the bending operation, and when the rollers 42 bear upon the outcr surface of the pipe, on the one hand, the burners 9 and So will be quite close to the respective collars 43; on the other hand, the arm 35 will be perpendicular to the corresponding end of the pipe.

A weight 3 is suspended from each collar 43.

The operation of each device A and B is as follows: The bending commences at a point near the collar 43, and proceeds at the same time to the ends and the middle of the pipe, the bending regions remaining at all times adjacent the bumers, so that the joint 36 remains at a constant I distance from the straight parts of the pipe, and

In this embodiment, the automatic stop-piece 20 may be connected with the arm so that it will engage the arm 350. when the angle between the two arms has reached the desired value.

The modified device shown in Fig. 6 differs from the preceding only by the fact that the arms 35 and 35a are connected together and are carried by a joint 36 which is itself carried by an arm 40 integral with a sleeve 43 secured to the middle part of the pipe. The burners are set in motion by levers M and Me which are secured to the arms 35 and 35a which carry rollers 42 and 42a rolling upon the ends of the pipe. The length of the arm 40. and the length of the levers 4| and Ma, as well as their direction, are such that the arms 35 and 350 will always be at right-angles to the ends of the pipe. According to the embodiment shown in Fig. '1,

the pipe I (or like piece) to be bent is placed upon two fixed supports 34, 34a. On either side of the vertical plane MM equidistant from the supports 34, are located two bending devices A and B. which are symmetrical with reference to the said plane, and each device comprises two burners. Each device is provided with a collar 43 by which it is secured to the pipe. The two .burners 3 and So will come into contact.

that, owing to the roller 42 and the arm 4|, the arm 35 will always be perpendicular to the corresponding straight part. In consequence, the two burners move away from one another by an amount which is proportional to the bending angle obtained and to the radius of curvature which is equal to the length of the arms 40. The arm 35 actuates the arm 31 by means of the links 45.

Two bends are thus obtained, each of which has for its middle one of the two collars 43. As the bending operation proceeds, these bends will increase at the same time at the right and left, until they come together in the plane MM so as to form a single bend. As this time, the. two The two joints 36 will also come together.

The advantage of this arrnagement is that it doubles the rate of working, and that it permits of obtaining, in a short time, bends having a great deflection. I

The two sets of burners might be located in different planes in order to obtain a warped bend. The weights 8 may be replaced by a single weight, and if necessary, this may consist of the pipe itself.

According to the embodiment shown in Fig. 8. which is only applicable to hollow pieces, such as pipes, the pipe I to be bent, rests upon two supports 34, 34a, for instance two rollers. The said pipe is to be bent by a downward flexion. The bending stress is exerted by a weight 8 which is suspended from the pipe by a, member 46 which bears upon the pipe at 41. Instead of acting directly upon the member 46, the weight is prefercollars 43 are mounted on the pipe at two points which are spaced at a distance equal to one-- half the developed length of the bend which is to be. obtained.

Each of the said collars carries an arm 40 the length of which is equal to the radius of the bend to be obtained, and is terminated by a joint 36. The said joint carries two arms 35 and 31 upon the ends of which are mounted two burners 9 and 9a. A system of links pivoted to a guide 44 slidable on the arm 46, assures for the arms 35 and 31 a symmetrical position with reference to the support 46.

The arm 35 is secured to a rod 4| having on its end a roller 42.

ably suspended on a cable (or chain) 43 which passes over roller--49 and 50 carried by member 46. The ends of the cable are attached to the ends of the pipe by collars 5| and 52, or otherwise. The cable is preferably attached in an elastic manner to one of the collars, for instance the collar 5I, by means of a spring 53. Owing to the said cable, the lower generatrices of the pipe, i. e. those situated at theouter part of the bend or elbow, are subjected to a compression the value of which depends upon the mass of the said weight and upon the degree of inclination of the strandsab and ac of the cable. (It should be noted that one or more stretchers may be employed.)

To the left-hand end of the pipe I is rigidly secured, by two collars 54 or otherwise, a supporting frame (55, 56). Upon the said frame is pivotally mounted, on a horizontal axis 51 passing through the centre of the bend to be obtained, a triangular support (55a, 56a). The arms 55 and 55a of said supports have a length which is equal to the radius of the desired bend.

The arm 550. carries a sleeve 58 consisting of heat-insulating material (ceramic or the like), which surrounds the pipe I. The second arm 56a bears upon the pipe by a roller 59 adapted to roll upon the pipe. the dimensions of the said arm and roller being such that the arm 55a will be perpendicular to the portion of the pipe which is to be bent.

In the interior of the pipe is mounted a small rolling carriage 60 carrying a burner 6| using propane or other gas or combustible fluid. The said burner 6| is preferably positioned excentrically. It is located with reference to the axis of the pipe. on the same side as the centre of the bend to be obtained, in such manner that it will more strongly heat, as desired, the concave generatrices.

To the carriage 68 is attached the end oPa cable or like connecting member 62, which issues from the pipe I and passes over a roller 63 mounted upon the pipe, passes over another roller 64, also mounted on the pipe, and finally upon a roller 65 whifh is mounted, for instance, upon a member 66 secured to the support 55, 56. At the end of the cable 62 is suspended a weight 6'l.- To the cable 62 is attached at 6! an auxiliary cable or other flexible connecting member 69 which passes over the roller 64 and is attached at 18 to the oscillating support 55a, 56a. The cable 69 and the corresponding part of the cable 62 from the carriage 60 to the point 68) have such lengths that the burner 6| will always be situated, whatever be the position of the support 55a,

56a, adjacent the insulated sleeve 58 which serves 1 to reduce the heat loss to the outside.

The operation is as follows.

At the start, with the pipe I being straight, the arm 55a of support 55a, 56a is in contact with the frame 55. 56. As the bending of the pipe proceeds, under the action of the bending stress due to the weight 8, the support 55a, 56a will pivot about the axis 57 in the direction of the arrow I. As the bending takes place at any one time in the plane of the burner, and as the joint 51 will thus always be at the same distance from the straight part of the pipe during the bending operation, the arm 550 will always be perpendicular to the pipe I, and the burner 6| will follow the support 55a, 56a by means of the cable 62 and 69, while remaining constantly aligned with the heatinsulating sleeve 58. This displacement is equal, at each instant, to the product of the desired radius of curvature multiplied by the bending angle already obtained. From this it will result that the curvature obtained at each point of the pipe I is constant, and hence that the bend or elbow thus obtained will have the form of a perfectly regular arc of a circle.

Instead of heating the pipe I in the interior only by means of a burner 6I having an eccentric position, it is also possible to make use of a burner situated on the axis, and to employ a differential heating, by using at the outside one or two auxiliary burners II which act upon the concave wall. In this case, the heat-insulating sleeve 58 will obviously be replaced by an outer furnace wall.

In the case of heating by propane or gas, it will evidently be necessary to prevent the prodnets of combustion from issuing from the end of the pipe on the left-hand side of the figure. The draught may be facilitated by the use of a chimney placed at the end of the pipe, or a smoke suction device, or the like.

Instead of heating by an inner propane burner,

it is also possible to heat internally by means of a. radiating heater heated electrically by means of resistances. The resistances can be best placed along the generatrices of an insulating body and may be so designed that the heating will vary gradually, from the outer convex part to the inner concave part. In this case, the electric heater can be maintained in an exactly concentric position, making use only of the unsymmetrical radiation of the heater inself.

In the case of electric heating, the yield can be increased ascompared with the heating by burners, as the pipe can be entirely stepped up at one end, while leaving at the other end only a small opening for the traction cable of the burner and the electric cables.

When electric heating is employed, it is possible to use simultaneously two electric heaters located symmetrically in the pipe to be bent, and to replace, for thispurpose, the fixed frame 65, 56 by a device which is symmetrical with the device (56a, 56a, 58, 60, 62, 69) with reference to the vertical plane passing through the axis of the joint 6'! connecting these two devices, which axis is now rigidly connected with the middle part of the pipe to be bent.

The automatic bending action which, is obtained according to the invention has numerous advantages, and chiefly the following:

A great rapidity, because of the burner or burners remaining in front of each section of the pipe only for the exact time required for the heating and the bending of this section; as soon as the bending takes place, the burner is moved farther on, by means of the mechanical device above described. In this manner. the time required for the manufacture of bends made of centrifugated cast iron is reduced by to 70% as compared with the processes hitherto employed. E

A considerable saving of fuel, owing to the great rapidity of the operation.

A substantial saving of labour, as the presence of a workman to look after the machine is by no means necessary, and the men are only required to place the pipe, or other piece to be bent in position, to light the burners, and to remove the bent piece when the automatic stopping device has acted.

'The production of perfectly regular pieces, the radius of curvature is exactly constant, owing to the principle of the invention itself, and it can be determined in advance, according to the requirement of use.

The regular movement of the burner or burners along the pipe or other piece, as the motion of the burner can be regulated to suit any particular case, taking due account of the dimensions of the piece and the metallurgical properties of the metal.

On the other hand, the process permits of obtaining'not only bends having a constant radius,

but also curves of variable radius, such as spirals. or warped bends, such as helices.

Referring particularly to the embodiment shown in Fig. 1, it is simply necessary, in order to obtain a spiral, that the movement of the burner 9 should not be proportional to the movement of the collar III, but that it varies dependent on this movement according to a predetermined formula. It will suffice, for this purpose, to replace the pulleys II by cams having a suitable outline.

In order to obtain a helical elbow, it is simply necessary, while displacing the burner 9, to turn the straight part of the tube or other piece to be bent about its longitudinal axis and proportionally to the bending angle already obtained.

Obviously. the invention is not limited to the embodiments herein described and shown, which are given solely by way of example.

For instance it is possible, according to the invention, to bend tubes or other pieces while maintaining stationary the burner or burners and by displacing the tube, by automatic methods analogous to the ones described, through a distance proportional to the desired radius of curvature and-to the bending angle already obtained.

On the other hand, according to the feature of the operation to be performed, use may be made of any number of burners placed adjacent each other or spaced apart. The burner or burners may be of any type, adapted for any suitable fuel such as petroleum, butane, propane, illuminating gas, blast-fumace gas, etc. The burners can be replaced by other heating means, such as electric heating apparatus.

In all cases, the bending operation can be facilitated by any of the usual processes, and chiefly, in the case of cast iron pipes, by the compression of the inner wall of the pipe to be bent.

Having now described my invention what I claim as new and desire to secure by Letters P'atentis. I

l. A process for bending pipes which comprises clamping a portion of a pipe in a freely overhanging position on one side of a part to be bent of said pipe, applying a bending force to a point on the said overhanging portion of said pipe, located on the other side of said part to be bent, and causing a heating source to be displaced automatically along said part to be bent towards said clamped portion at a constant distance from the axis of said clamped portion, said displacement being effected by the movement of said point to which said bending force is applied, whereby the degree of curvature obtained is a functionof said bending force and of the effect of said'heating source.

2. A process as claimed in claim 1, in which,

in order to obtain a circular bend, said displacement is made equal to the product of the angle of the curvature produced multiplied by the constant radius of curvature desired.

3. A device for bending pipes, bars, plates-and like pieces, comprising in combination means for fixedly holding one end of the piece to be bent, heating means adapted to locally heat said piece, a track parallel to the fixed part of said piece, a carriage movable on said track and supporting said heating means, a link pivotally connected at one end to said carriage and connected at its other end to the free end of said piece, a sector rigidly secured to said link, a flexible connecting member attached to and passing over said sector and a weightsuspended from the free end of said connecting member.

4. A device for bending pipes comprising in combination supporting means adapted to clamp said pipe in a freely overhanging position on one side of a part to be bent of said pipe, ambulant heating means for locally heating the pipe at the place to be bent, guiding means adapted to guide positively said heating means along said part to be bent so that said heating means always remains at a constant distance from the axis of the straight portion of the pipe clamped in said supporting means, and means for producing simultaneously a bending stress on the pipe on the other side of said part to be bent and a displacement of said heating means towards said clampedportio'n of the pipe according as the bending progresses.

5. A device as claimed in claim 4, further comprising stop means for automatically limiting the relative displacement between said heating means and said pipe.

6. A device as claimed in claim 4, further comprising stop means for automatically limiting the relative displacement between said heating means and said pipe, and adapted to cut of! the heat producing fluid feeding said heating means.

PIERRE BOISSOU. 

